Automated ball mounting process with solder ball testing

ABSTRACT

An automated ball mounting process is disclosed in which solder balls are tested by heating the solder balls to a temperature between the eutectic temperature of lead-tin and the melting temperature of a lead free solder ball. If the heated solder balls melt they are standard solder balls. If they do not melt they are lead free solder balls. Solder balls that are input into the automated ball mounting process are automatically tested to determine solder ball type. When the test indicates that the wrong type of solder ball is being used an error message is indicated and the solder ball mounting process stops.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 10/990,123 filed on Nov. 16, 2004 and claims the benefit ofMalaysian Patent Application No. PI20042408, filed on Jun. 18, 2004which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the field of semiconductor devices.More specifically, the present invention relates to solder ball mountingprocesses and systems.

BACKGROUND ART

Automated solder ball mounting systems have been developed that quicklyand accurately attach solder balls to substrates. The solder ball typemost commonly used in these systems is the standard solder ball.Standard solder balls are formed of a lead-tin alloy. However, forenvironmental reasons there has been an increasing need for the use oflead free solder balls.

The requirement that a manufacturing facility be able to attach bothstandard solder balls and lead free solder balls has forced somemanufacturing facilities to purchase additional dedicated ball mountingsystems to mount lead free solder balls. However, when both standardsolder balls and lead free solder balls are used in the samemanufacturing facility, workers can accidentally input the wrong type ofsolder ball into a solder ball mounting system. This can result innumerous defective products being fabricated before the problem isdiscovered.

To minimize the potential for defective products resulting fromattachment of the wrong solder ball type, sample parts are produced andare sent to a laboratory for analysis before the start of production.Typically these labs determine solder ball type using x-ray fluorescentequipment that indicates tin content. The lab test delays the start-upof production, reducing equipment utilization rates and reducingefficiency. Moreover, though testing prior to start up of productionassures that the production process will start off with the correctsolder ball type it is still possible that a worker may input the wrongtype of solder ball into the ball mounting system during production.

Accordingly what is needed is an automated ball mounting process andsystem that will minimize or eliminate product defects resulting fromthe use of the wrong solder ball type. Also, there is a need for amethod and apparatus that meets the above need and that can mount bothstandard solder balls and lead free solder balls. The present inventionmeets the above needs.

DISCLOSURE OF THE INVENTION

The present invention provides an automated solder ball mounting processand system in which solder ball type is tested in order to assure thatthe correct type of solder ball is being used. This results in reduceddown time and reduced defect rates.

An automated solder ball mounting process and an automated ball mountingsystem are disclosed in which solder balls are tested to determinesolder ball type. When the test is performed and the wrong solder balltype is being used an error message is indicated and the solder ballmounting process is stopped. This prevents product defects that canresult from the use of the wrong solder ball type. In addition, a singlesolder ball mounting system can be used to attach both standard solderballs and lead free solder balls while preventing product defects thatcan result from use of the wrong solder ball type. The use of a singlesystem instead of two dedicated systems results in significant costsavings as compared to prior art processes that use one dedicated systemfor standard solder balls and a second dedicated system for lead freesolder balls.

By preventing the attachment of the wrong solder ball type, the methodand apparatus of the present invention results in reduced productdefects. In addition the method and apparatus of the present inventionallows for quicker start-up of the manufacturing process as there is noneed to send solder ball samples to a test lab and wait for testresults.

These and other advantages of the present invention will no doubt becomeobvious to those of ordinary skill in the art after having read thefollowing detailed description of the preferred embodiments, which areillustrated in the various drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention.

FIG. 1 is a flow chart that illustrates an automated ball mountingprocess in which solder balls are tested to determine whether they arestandard solder balls or lead free solder balls in accordance with oneembodiment of the present invention.

FIG. 2 is a diagram that illustrates an automated ball mounting systemin accordance with one embodiment of the present invention.

FIG. 3 is a diagram that shows the components of a solder ball testingassembly and illustrates a front cross-sectional view of a test block inaccordance with one embodiment of the present invention.

FIG. 4 is a diagram that shows a top view of the test block of FIG. 3 inaccordance with one embodiment of the present invention.

FIG. 5 is a diagram that shows a side cross-sectional view of the testblock along section A-A of FIG. 3 in accordance with one embodiment ofthe present invention.

FIGS. 6A and 6B is a flow chart that illustrates a process for testingsolder balls to determine solder ball type in accordance with oneembodiment of the present invention.

The drawings referred to in this description should be understood as notbeing drawn to scale.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thepreferred embodiments, it will be understood that they are not intendedto limit the invention to these embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description of the present invention, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. However, it will be obvious toone of ordinary skill in the art that the present invention may bepracticed without these specific details. In other instances, well-knownmethods, procedures, components, and circuits have not been described indetail so as not to unnecessarily obscure aspects of the presentinvention.

Standard solder balls are composed of a lead-tin alloy that isapproximately 63 percent tin (Sn) and 37 percent lead (Pb). Eutectictemperature is the lowest temperature at which a mix of two materialswill melt. Standard solder balls melt at the eutectic temperature oflead-tin which is 180 degrees Centigrade. This temperature issignificantly less than the melting temperature of lead alone (327degrees Centigrade) and the melting temperature of tin alone (231degrees Centigrade).

The melting temperature of lead free solder balls is typically muchhigher than the eutectic temperature of lead-tin. One type of commonlead free solder ball has 96.5 percent Sn, 3 percent silver (Ag) and 0.5percent copper (Cu) (hereinafter referred to as a Sn/Ag/Cu lead freesolder ball) that melts at 217-219 degrees Centigrade. Another commonlead free solder ball includes 96.5 percent Sn, 2 percent Ag, 0.75percent Cu and 3 percent Bismuth (Bi) (hereinafter referred to as aSn/Ag/Cu/Bi lead free solder ball) that melts at 210-216 degreesCentigrade.

The methods and apparatus of the present invention take advantage of thedifference between the melting temperature of standard solder balls andthe melting temperature of lead free solder balls by heating solderballs to a temperature greater than the eutectic temperature of lead-tinand less than the melting temperature of lead free solder balls. If thesolder balls melt they are standard solder balls. If they do not meltthey are lead free solder balls.

FIG. 1 illustrates an automated ball mounting process 100 in whichsolder ball type is determined. Referring now to steps 101-102substrates and solder balls are received into the automated process. Thereceived substrates are sequentially advanced through the process ofsteps 103-105, with flux dispensed onto each substrate as shown by step103 and solder balls dispensed onto each substrate as shown by step 104.The substrates with attached arrays of solder balls are then output asshown by step 105. These substrates can then be loaded into an oven toreflow the solder balls.

Referring now to step 106 some of the solder balls that are input intothe automated process are tested to determine whether the tested solderballs are lead free. This test is automatically performed during theautomated ball mounting process and does not require that solder ballsto be tested be removed from the ball mounting system. As shown by step107-109, when the process requires lead free solder balls and when thetest indicates that the tested solder balls are not lead free an errorindication is provided to the operator and production is discontinued bystopping the automated ball mounting process.

Similarly, as shown by step 107 and 109-110, when the process does notrequire lead free solder balls and when the test indicates that thesolder balls are lead free solder balls an error indication is generatedand production is discontinued by stopping the automated ball mountingprocess.

When an error is detected in accordance with step 109 at start-up theprocess of steps 103-105 is never initiated, preventing defectiveproducts from being fabricated. When an error is detected in accordancewith step 109 during the production process of steps 103-105, theprocess of steps 103-105 is stopped and an error indication is generatedto prevent the manufacture of defective products.

As shown by step 107-108 and 111, when the process requires lead freesolder balls and when the test indicates that the tested solder ballsare lead free solder balls production is started or continued.Similarly, as shown by steps 107 and 110-111, when the process requiresstandard solder balls and when the test indicates that the tested solderballs are standard solder balls production is started or continued. Moreparticularly, when a match is detected in accordance with step 111 atstart-up the process of steps 103-105 is initiated, starting theproduction process. When a match is detected in accordance with step 111during the production process of steps 103-105, the process of steps103-105 is continued. In the present embodiment the processes of steps106-111 are performed in a fully automated manner, without any need foroperator intervention, leading to automated shut-down, start-up orcontinuation of the production process.

Referring now to FIG. 2, an automated ball mounting system 20 isdisclosed that can be used to perform process 100. Automated ballmounting system 20 receives substrates (step 101) at input magazines 1a-d. In the present embodiment input magazines 1 a-d are slottedmagazines that can receive strip Ball Grid Array (BGA) substrates. TheBGA substrates can be Ceramic Ball Grid Array (CBGA) substrates, PlasticBall Grid Array (BGA) substrates or any other type of substrate that isadapted to receive an array of solder balls. The BGA substrates advancefrom slotted magazines 1 a-d to flux dispensing assembly 2 where flux isdispensed onto each BGA substrate.

Each BGA substrate then advances to the ball dispensing assembly 3 wheresolder balls are dispensed onto each BGA substrate. In the presentembodiment ball dispensing assembly 3 includes a ball placement tool anda ball pattern tool that include ejection pins that eject solder ballsonto each BGA substrate so as to form the required BGA pattern.Alternatively, ball dispensing assembly 3 can use screen printing or anyother methodology for dispensing solder balls onto BGA substrates.

In the present embodiment ball dispensing assembly 3 includes a solderball canister that receives solder balls that are input into automatedball mounting system 20. The solder ball canister can be color coded toindicate the type of solder balls that it should contain. In the presentembodiment the solder ball canister for receiving lead free solder ballsis colored green, and the solder ball canister for receiving standardsolder balls is a different color.

In the present embodiment ball dispensing assembly 3 is quickly andeasily convertible from dispensing one type of solder ball to dispensinga different type of solder ball. This can be done by removing the solderball canister and any residual solder balls in ball dispensing assembly3 and replacing the solder ball canister with a different type of solderball canister. For example, conversion from dispensing lead free solderballs to dispensing standard solder balls is accomplished by removingthe lead free solder ball canister, removing any residual lead freesolder balls in dispensing assembly 3 and installing a standard solderball canister. Similarly, conversion from dispensing standard solderballs to dispensing lead free solder balls is accomplished by removingthe standard solder ball canister, removing any residual standard solderballs in dispensing assembly 3 and installing the lead free solder ballcanister. This allows for using the same automated ball mounting system20 for attaching both lead free solder balls and standard solder balls.

In the present embodiment automated ball mounting system 20 includes aconveyor system 7 that is coupled to control unit 6. Conveyor system 7is operable to move BGA substrates to the different stations within ballmounting system 20. In the present embodiment conveyor system 7 includesone or more conveyor belts that move BGA substrates from input magazines1 a-d to flux dispensing assembly 2, ball dispensing assembly 3, andoutput substrates having an array of solder balls attached thereto.

Automated ball mounting system 20 includes imaging system 8 that iselectrically coupled to control unit 6. Imaging system 8 generatesimages at various locations within ball mounting system 20 that aretransmitted to control unit 6. Control unit 6 is operable to control theoperation of some or all of the components of automated ball mountingsystem 20. In the present embodiment control unit 6 is a computingdevice that includes a processor, memory storage, one or more data inputdevices and one or more data output devices.

By operation of control unit 6 the operator can control the operationsof each of the components of automated ball mounting system 20. In thepresent embodiment control unit 6 is operable upon receiving images fromimaging system 8 to analyze the received images. Control logic withincontrol unit 6 uses the analysis of images and input from components 1a-d, 2-3, 5 and 7-8 for controlling the operation of automated ballmounting system 20.

Solder ball testing assembly 5 is operable for determining the type ofsolder balls in ball dispensing assembly 3. In the embodiment shown inFIGS. 3-5 solder ball testing assembly 5 includes a pick and placemechanism 56 that is operable to move solder balls to be tested fromball dispensing assembly 3 to test block 40. In the present embodimentpick and place mechanism 56 removes solder balls directly from thesolder ball canister installed in ball dispensing assembly 3 and movesthem onto test block 40.

Referring now to FIGS. 3-5 solder ball testing assembly 5 includes aplate 41 having indentations 43 within the top surface of plate 41 forreceiving solder balls. Openings 42 extend through plate 41 below eachof indentations 42. Tray 49 extends below openings 42 to retain meltedsolder ball material. In the embodiment shown in FIGS. 3-5, plate 41 isa thin flat sheet of metal. However, alternatively, plate 41 can be anytype of receptacle that can contain one or more solder ball and that canallow for melted solder ball material and unmelted solder balls to beremoved therefrom.

Heating device 46 is thermally coupled to plate 41 by heater block 45.In the present embodiment plate 41 and heater block 45 are formed of amaterial that is conductive to heat such that heat from heating device46 is conveyed through heater block 45 and through plate 41 so as toheat any solder balls that are placed in indentations 43. Heater block45 can be metal or any other material that readily conveys heat. Ceramicblock 48 attaches to heater block 45 so as to thermally insulate heaterblock 45 from the other components of ball mounting system 20.

Thermocouple 47 is operable to determine temperature within heatingblock 45. In the present embodiment both thermocouple 47 and heater 46are electrically coupled to control unit 6. Control logic within controlunit 6 is operable to turn heating device 46 on and off as necessary tomaintain the temperature of plate 41 within a given temperature range.

In the present embodiment plate 41 is maintained at a temperaturebetween the eutectic temperature of lead-tin (180 degrees Centigrade)and the melting temperature of lead free solder balls. The term “meltingtemperature of lead free solder balls” can be the melting temperature ofa single type of lead free solder ball or can be the lowest meltingtemperature for two or more different types of lead free solder balls.More particularly, when a manufacturing process only uses one type oflead free solder ball the temperature used would be the meltingtemperature of that particular type of solder ball. For example, themelting temperature of a Sn/Ag/Cu lead free solder ball is 217 degreesCentigrade. The melting temperature of a Sn/Ag/Cu/Bi lead free solderball is 210 degrees Centigrade. When the process uses multiple differenttypes of lead free solder balls the melting temperature of lead freesolder balls would be the lowest melting temperature of any of thedifferent types of lead free solder balls used. When the lead freesolder balls can be either Sn/Ag/Cu lead free solder balls orSn/Ag/Cu/Bi solder balls the melting temperature would be 210 degreesCentigrade.

As lead free solder balls can be made of different materials anddifferent percentages of the various alloys can be used, in oneembodiment a temperature range of from 180-210 degrees Centigrade isused. This will differentiate standard solder balls from Sn/Ag/Cu leadfree solder balls, Sn/Ag/Cu/Bi solder balls, and any other type of leadfree solder ball having a melting temperature greater than 210 degreesCentigrade.

In another embodiment a temperature range of from 180-200 degreesCentigrade is used. This will differentiate standard solder balls fromSn/Ag/Cu lead free solder balls, Sn/Ag/Cu/Bi solder balls, and any othertype of lead free solder ball having a melting temperature greater than200 degrees Centigrade.

In one specific embodiment a temperature range of 185-195 degreesCentigrade is used. This will differentiate standard solder balls fromany lead free solder ball having a melting temperature of greater than195 degrees Centigrade.

Though the present embodiment uses a heating device 46 that is thermallycoupled to plate 41, alternatively a heating device could be used thatis located proximate plate 41 for heating solder balls that are placedon plate 41. For example, a heating device could be used that is locatedabove plate 41 that supplies radiant heat so as to directly heat anysolder balls that are placed on plate 41. Moreover, it is appreciatedthat heating device 46 could generate heat using electricity, naturalgas, or any other fuel source, and could transmit that heat throughdirect contact, direct or indirect radiation, including thermal ormicrowave radiation.

Vacuum system 52 is coupled to plate 41 for removing melted solder ballsfrom plate 41. In the present embodiment vacuum system 52 is coupled tocavity 50 beneath plate 41 by hose 51 such that vacuum system 52 canapply suction to openings 42.

Pick-and place mechanism 56 is located proximate to plate 41 andproximate to ball dispensing assembly 3. In the present embodiment pickand place mechanism 56 is operable to pick up solder balls from thesolder ball canister installed in ball dispensing assembly 3 and placethem into indentations 43. Also, pick and place mechanism 56 is operableto remove unmelted solder balls and place them in a trash receptacle.

Camera 54 is operable to generate images of the top of plate 41. In thepresent embodiment camera 54 is electrically coupled to control unit 6such that operation of camera 54 generates images that can beinterpreted by control unit 6 to determine whether solder balls arepresent in indentations 43. In the present embodiment camera 54 andcontrol unit 6 form a detection system that is operable to determinewhether solder balls are present in indentations 43. However,alternatively an additional computing device could be included withinsolder ball testing assembly 5 for analysis of images from camera 54 todetermine whether solder balls are present.

FIG. 6 illustrates a process 200 for testing solder balls to determinesolder ball type in which test block 40 of FIGS. 3-5 is used todetermine solder ball type. First, as shown by step 201 plate 41 isheated. More particularly heating device 46 is turned on andthermocouple 47 is monitored to determine whether plate 41 has reachedthe required temperature range. Referring to steps 202-203 if thetemperature of plate 41 is within the required operating range theprocess will proceed to step 203. If the temperature of plate 41 is notwithin the required temperature range as shown by steps 202 and 216 asystem failure has occurred and an error indication will be provided tothe operator.

As shown by step 203 once plate 41 has reached the required temperaturerange plate 41 is cleared. More particularly, if thermocouple 40indicates that the correct operating temperature has been reached,camera 54 is activated to generate images of the top of plate 41. Theseimages are analyzed by control unit 6 to determine where on plate 41unmelted solder balls are located. If any unmelted solder balls aredetected, they are removed using pick and place mechanism 56.

Referring now to step 204, the system then checks to determine whetherthe top of plate 41 is clear. In the present embodiment, images fromcamera 54 are generated that show the top of plate 41. Control unit 6analyzes the images to determine whether any solder balls are present onthe top surface of plate 41. If the top of plate 41 is clear (no solderballs are present) solder balls that are to be tested are moved ontoplate 41 as shown by step 205. In the present embodiment solder ballsare removed from ball dispensing assembly 3 to indentations 43. In oneembodiment all of indentations 43 are filled with solder balls.Alternatively only some of indentations 43 are filled with solder balls.In the present embodiment control unit 6 is programmable such that thenumber of solder balls to be tested can be changed depending on theparticular process schedule and quality control requirements.

Referring now to step 206 the system checks to determine where solderballs are located on plate 41. If no solder balls are present on plate41 a failure has occurred as shown by steps 206 and 216 and an errorindication is provided to the operator. In one embodiment, images fromcamera 54 are generated after the placement of solder balls intoindentations 43, and before the solder balls have had a chance to melt.This image can be generated immediately after the placement of eachsolder ball into an indentation 43. However, alternatively a singleimage is generated after all of the solder balls have been placed.Control unit 6 is operable to analyze the images for determining whetheror not a solder ball is present in each indentation 43. This stepprevents errors that would result if a solder ball were to be dropped ormisplaced.

Once all of the solder balls have been moved and are determined to bepresent on plate 41, a timer is initiated. Referring to steps 207-208,after a predetermined time period has elapsed, vacuum system 52 isengaged so as to apply a vacuum to each of openings 42. If the solderballs melt the suction will draw the solder ball material throughopenings 42 and it will fall into tray 49. In the present embodiment thetime period is programmable and is a time sufficient for standard solderballs to melt.

Referring now to step 209, images from the camera 54 are generated andare analyzed to determine whether the solder balls determined to bepresent in step 206 have melted. If the images indicate that the solderballs are still present on plate 41 the solder balls are lead free asshown by steps 209 and 213. As shown by steps 209-210 if the imagesindicate that the solder balls determined to be present in step 206 areno longer present on plate 41 then the solder balls were standard solderballs that melted. If solder balls remain on the plate, a solder ballremoval sequence can then be activated for removing all remaining solderballs on plate 41. Alternatively, the solder balls can be left on theplate 41 and can be cleared in step 203 of the following test.

Referring now to steps 211 and 214 when the type of solder ball does notmatch the type of solder ball required by the process an errorindication is generated as shown by step 215 and production is stopped.More particularly, if the process requires lead free solder balls andthe test indicates that the solder balls are standard solder balls, anerror indication is generated as shown by step 210-211 and 215 and theproduction process is stopped. The error indication can be any visual oraudible output that can be perceived by an operator such as, forexample, a bell, siren or other sound and/or an error message that isviewable on a display.

Similarly, when the process requires standard solder balls and the testindicates that the solder balls are lead free an error indication isgenerated as shown by step 215, and the production process is stopped.Referring to steps 210-212, if the process requires lead free solderballs, and the test indicates that the solder balls are lead free thereis a match between the solder balls tested, and the process requirementsand production will start (if the test is being performed uponinitiation of production) or will continue (if the test is beingperformed during production). Similarly, as shown in steps 212-214, whenthe process requires standard solder balls and the test indicates thatthe solder balls are standard solder balls, there is a match between thesolder balls tested, and production will start (if the test is beingperformed upon initiation of production) or will continue (if the testis being performed during production).

In the present embodiment, the operation of solder ball testing assembly5 is fully automated such that solder ball testing assembly 5automatically performs tests as required by its programming. Also,control logic within control unit 6 is operable to automaticallyinitiate the test sequence. In the present embodiment system 20 is fullyprogrammable and such that the timing of testing can be varied toaccommodate scheduling and quality control needs.

In the present embodiment a test is performed automatically each timethe solder ball attachment process is initiated so as to assure that theright type of solder balls are being used prior to manufacturing anyproduct. Also, testing is preformed periodically throughout the solderball attachment process. In the present embodiment tests are performedat predetermined time intervals after the initiation of the solder ballattachment process. In one embodiment, ball dispensing assembly 3includes a sensor that detects when the solder ball reservoir is low andtesting is also performed each time that the sensor indicates that thereservoir has been filled.

In the present embodiment, automated ball mounting system 20 is fullyautomated and is controlled by control unit 6 to automatically performall of the steps required for mounting solder balls and testing solderballs in accordance with product requirements. In one embodiment all ofthe components of automated ball mounting system 20 are contained in asingle integrated unit that includes a housing that encloses all of thecomponents of automated ball mounting system 20.

The process and apparatus of the present invention allow for thedetermination of solder ball type automatically and quickly, preventingproduct defects that can result from the use of the wrong solder balltype. In addition, a single solder ball mounting system can be used toattach both standard solder balls and lead free solder balls whilepreventing product defects that can result from use of the wrong solderball type. The use of a single system instead of two dedicated systemsresults in significant cost savings as compared to prior art processesthat use one dedicated system for standard solder balls and a seconddedicated system for lead free solder balls. In addition the process andapparatus of the present invention allows for quicker start-up of themanufacturing process as there is no need to send solder ball samples toa test lab and wait for test results.

The preferred embodiment of the present invention is thus described.While the present invention has been described in particularembodiments, it should be appreciated that the present invention shouldnot be construed as limited by such embodiments, but rather construedaccording to the following claims.

1. An automated ball mounting process in which solder balls aredispensed onto a substrate comprising: testing at least some of thesolder balls to determine whether the solder balls are lead free byheating the solder balls to be tested to a temperature between theeutectic temperature of lead-tin and the melting temperature of a leadfree solder ball and determining that the solder balls are not lead freeif they have melted; and generating an error indication when saidprocess requires lead free solder balls and when the test indicates thatsaid solder balls are not lead free.
 2. The process of claim 1 whereinthe testing at least some of the solder balls further comprises placingthe solder balls to be tested on a heated plate that includes openingsthat are coupled to a vacuum system, and wherein a vacuum is applied tothe openings to remove any melted solder balls.
 3. The process of claim2 wherein the determining whether the solder balls to be tested havemelted further comprises: generating an image of the plate; andanalyzing the image to determine whether solder balls are present. 4.The process of claim 2 wherein the testing at least some of the solderballs is performed automatically during the automated ball mountingprocess.
 5. The process of claim 2 wherein the heating the solder ballsto be tested further comprises heating the solder balls to be tested toa temperature between 180 degrees Centigrade and 210 degrees Centigrade.6. The process of claim 2 further comprising: stopping the automatedball mounting process when the process requires lead free solder ballsand when the test indicates that the tested solder balls are not leadfree.
 7. The process of claim 6 wherein the heating the solder balls tobe tested further comprises heating the solder balls to be tested to atemperature between 185 degrees Centigrade and 195 degrees Centigrade.8. The process of claim 6 wherein the heating the solder balls to betested further comprises heating the solder balls to be tested to atemperature between 180 degrees Centigrade and 200 degrees Centigrade.9. An automated ball mounting process comprising: receiving solderballs; testing at least some of the solder balls to determine whetherthe solder balls are lead free by heating the solder balls to be testedto a temperature between the eutectic temperature of lead-tin and themelting temperature of a lead free solder ball and determining that thesolder balls are not lead free if they have melted; and generating anerror indication when the process requires lead free solder balls andwhen the test indicates that the solder balls are not lead free; anddispensing some of the solder balls onto a substrate when the processrequires lead free solder balls and when the test indicates that thetested solder balls are lead free.
 10. The automated ball mountingprocess of claim 9 further comprising: stopping the automated ballmounted process when the process requires lead free solder balls andwhen the test indicates that the tested solder balls are not lead free.11. The automated ball mounting process of claim 9 wherein the testingat least some of the solder balls further comprises: moving the solderballs to be tested from a solder ball canister to a testing assembly;generating a first image of the solder balls to be tested; heating thesolder balls to be tested to a temperature between the eutectictemperature of lead-tin and the melting temperature of a lead freesolder ball; waiting a predetermined time period; generating a secondimage of the solder balls to be tested; analyzing the second image todetermine whether the solder balls to be tested have melted; andremoving solder balls to be tested that have not melted.
 12. Theautomated ball mounting process of claim 11 wherein the testing assemblyincludes a plate having one or more openings and wherein the solderballs to be tested are placed on the plate proximate the openings, theprocess further comprising: applying a vacuum to said openings so as toremove any of said solder balls to be tested that have melted.
 13. Theautomated ball mounting process of claim 9 wherein the testing at leastsome of the solder balls is performed at start-up of the automated ballmounting process.
 14. The automated ball mounting process of claim 13wherein the receiving solder balls further comprises attaching a solderball canister to an automated ball mounting system.
 15. The automatedball mounting process of claim 14 wherein the testing at least some ofthe solder balls is performed each time that a new solder ball canisteris attached.
 16. The automated ball mounting process of claim 15 whereinthe testing at least some of the solder balls is performed each timethat solder balls are added to the solder ball canister.
 17. A methodfor testing solder balls in an automated ball mounting processcomprising: moving solder balls to be tested from a solder ball canisterto a testing assembly; generating a first image of the solder balls tobe tested; heating the solder balls to be tested to a temperaturebetween the eutectic temperature of lead-tin and the melting temperatureof a lead free solder ball; waiting a predetermined time period;generating a second image of the solder balls to be tested; analyzingthe second image to determine whether the solder balls to be tested havemelted; and removing solder balls to be tested that have not melted. 18.The method of claim 17 further comprising applying a vacuum so as toremove solder balls that have melted prior to the generating a secondimage of the solder balls to be tested.
 19. The method of claim 18wherein the moving the solder balls to be tested from a solder ballcanister to a testing assembly further comprises moving the solder ballsto be tested to a plate having openings that extend therethrough, thevacuum applied to the openings to remove the solder balls that havemelted from the plate.
 20. The method of claim 19 wherein the heatingthe solder balls to be tested further comprises heating the plate.